January 4, 2001
Question from Rockford, Illinois, USA:
My eight year old son was diagnosed with type 1 diabetes two months ago His insulins (N and Humalog) were both opened then and have been stored in the refrigerator, except to transport to another destination. His bedtime blood glucose readings have been quite high for the past five days or so. He has been anywhere from 220-384 mg/dl [12.2-21.3 mmol/L], normally he would be in 100-150 mg/dl [5.6-8.3 mmol/L] range. I know that some of the highs are related to holiday activities and were expected! The problem seems to be related to his dinner Humalog dosing. I have made small adjustments using the theory that he now requires more insulin. This has not solved the problem.
Could it be that we need a fresh vial of Humalog? Is two and one-half months a normal shelf life of Humalog? Both our endocrinologist and CDE have stated to expect at least three months. I know that Lilly states one month. Just curious as to your experience.
My experience has been that opened vials of insulin, the NPH and the Humalog should be replaced monthly. The unopened bottles that have been refrigerated should be okay until their expiration date. Regardless of how insulin has been stored and how long it has been open, I always instruct people to try using new vials when increases that should be working don’t seem to be effective. It never hurts to rule out the possibility that there may a problem with the insulin.